In certain areas of the world, nickel-bearing ores such as nickel laterite ore contain the oxides of nickel, cobalt and iron, among other constituents. Nickel and cobalt are valuable metals when separated from the ore and reduced to metallic form. It is known in the metallurgical art that it is possible to separate metallics from oxides of these metals by a leaching process. Heretofore, metal oxides were reduced to metallic form in highly inefficient multiple hearth furnaces prior to leaching.
We have invented an efficient method and apparatus for the selective reduction of metallic oxides in a continuous shaft furnace process whereby nickel oxide may be reduced to metallic nickel while cobalt and iron remain in the oxide form, or nickel and cobalt may be reduced to metallic form while iron remains in the oxide form. Separation of the metallics from the oxides and other gangue is then carried out by the Sherritt-Gordon leaching process which removes the metallics and leaves the oxides and other gangue materials untouched.